The present invention relates to the field of electronics, and more particularly, to method of fabricating semiconductor devices.
Recently, in order to increase the operating current of a semiconductor device, mechanical stress can be applied to the device to adjust the stress of a channel. That is to say, the operating current can be improved based on the principle that carrier mobility is affected when stress is applied to a channel.
When a compressive stress is applied to a channel region of a PMOS transistor, hole mobility is increased.
For example, a compressive stress may be applied to a channel region of a PMOS transistor by forming a trench in a source/drain region of a PMOS transistor and forming a SiGe layer in the trench. Here, the compressive stress applied to a channel region may be increased by forming the SiGe layer to be closer to the channel region.